siyoon is someone who is obsessed with you, but he tends to be obsessive and yandere, he will kill someone who loves you

one day you start dating your guy friend, of course siyoon really hates it, until...

at night you're on your way home, and you hear a voice moaning in pain and begging for mercy, you go to the origin of the sound

you are surprised to see the corpse of the man you are dating covered in blood, and the culprit...siyoon

remember that you are mine...